This compound, 2-(2-((tert-butyldiphenylsilyl)oxy)ethoxy)ethanol, is a mono-protected derivative of diethylene glycol with a tert-butyldiphenylsilyl (TBDPS) group shielding one hydroxyl function. It functions as a key building block and intermediate in organic synthesis, enabling selective functionalization at the unprotected hydroxyl group while the TBDPS moiety provides stability under basic, neutral, and certain acidic conditions. This orthogonality is crucial for multi-step syntheses of complex molecules, including pharmaceuticals, oligonucleotides, peptides, and polymeric materials. The protecting group can be selectively deprotected using fluoride sources like TBAF, revealing the second hydroxyl for further elaboration. Its applications extend to the development of linkers, conjugates, and specialty additives in materials science and biochemistry.